It is known to control active devices of a vehicle according to a certain detected threshold. Such active devices may comprise for example occupant restraints, and deployable aerodynamic devices such as spoilers and aerofoils.
The threshold may be determined by, for example proximity to an obstacle, or simply in response to reaching a predetermined vehicle speed. An aerofoil may for example be deployed to enhance vehicle performance.
There may however be an inevitable delay in vehicle response as the measured parameter increases in value toward the threshold, and it would be desirable to provide compensation whereby this delay is eliminated or at least ameliorated during certain conditions of use of the vehicle.
In particular, the lateral acceleration of a vehicle typically peaks just prior to a vehicle exiting a corner, thus causing an inherent delay in actuation or deployment of an active device of the vehicle in response to high cornering forces, where the device is triggered at a threshold.
The active device may be a motorized seat belt. During vehicle cornering, a vehicle occupant is generally moving before the active device is deployed, and is typically arrested abruptly by a locked or retracting seat belt. This solution is thus not optimised for occupant comfort, and may be irritating if the threshold is set too low because the active device(s) will be repeatedly deployed. On the other hand a high threshold permits greater movement of an occupant before deployment, and a correspondingly higher contact load as the restraint has effect.
In the case of an aerodynamic device, the earlier and faster the deployment, the more effective will be the action of the device on the vehicle.